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Deep Galaxy survey at 6.75mu M with the ISO satellite
Elbaz, D.; Omont, A.; Eales, S. +8 more
Deep 6.75mu m mid-IR ISOCAM observations were obtained from the Canada-France Redshift Survey (CFRS) 1415+52 field with the Infrared Space Observatory. The identification of the sources with optical counterparts is described in detail, and a classification scheme is devised which depends on the S/N of the detection and the inverse probability of c…
Does the Sun Have a Full-Time Chromosphere?
Kalkofen, Wolfgang; Ulmschneider, Peter; Avrett, Eugene H.
The successful modeling of the dynamics of H2v bright points in the nonmagnetic chromosphere by Carlsson & Stein gave as a by-product a part-time chromosphere lacking the persistent outward temperature increase of time-average empirical models, which is needed to explain observations of UV emission lines and continua. We discuss the…
Optical and X-ray variability in the least luminous active galactic nucleus, NGC 4395
Terlevich, R.; Lira, P.; Lawrence, A. +3 more
We report the detection of optical and X-ray variability in the least luminous known Seyfert galaxy, NGC 4395. Between 1996 July and 1997 January the featureless continuum changed by a factor of 2, which is typical of more luminous AGN. The largest variation was seen at shorter wavelengths, so that the spectrum became `harder' during higher activi…
High-resolution optical and infrared spectroscopic observations of CIR X-1
Wu, Kinwah; Fender, Robert; Johnston, Helen M.
We present new optical and infrared (IR) observations of Cir X-1 taken near apastron. Both sets of spectra show asymmetric emission lines. Archival optical observations show that an asymmetric Hα emission line has been in evidence for the past 20 years, although the shape of the line has changed significantly. We present an eccentric (e~0.7-0.9) l…
Fractal Analysis of Michelson Doppler Imager Magnetograms: A Contribution to the Study of the Formation of Solar Active Regions
Meunier, N.
In this paper a fractal analysis of active regions observed by the Michelson Doppler Imager (MDI) instrument on the SOHO spacecraft is performed. The purpose of such an analysis is to study the shape of these magnetic regions via their fractal dimension, which characterizes their complexity, and to deduce some information on the processes that led…
Infrared Space Observatory Observations of IRAS 16594-4656: A New Proto-Planetary Nebula with a Strong 21 Micron Dust Feature
Manteiga, Minia; García-Lario, Pedro; Manchado, Arturo +1 more
Based on ISO short-wavelength spectrograph (SWS) + long-wavelength spectrograph (LWS) observations, IRAS 16594-4656 is identified as a new member of the rare class of C-rich proto-planetary nebulae with the 21 µm dust feature in emission. In addition, the major polycyclic aromatic hydrocarbon (PAH) emission bands at 3.3, 6.2, 7.7, 8.6, and 1…
Hubble Space Telescope Observations of the Dusty Small Magellanic Cloud H II Region N88A
Garnett, D. R.; Skillman, E. D.; Dufour, R. J. +5 more
We present results from the analysis of Hubble Space Telescope Faint Object Spectrograph (FOS), WFPC1, IUE, and Cerro Tololo Inter-American Observatory 4 m observations of the morphology, physical conditions, and chemical abundances in the anomalous H II region N88A in the Small Magellanic Cloud. Not only is N88A unusual among SMC H II regions bec…
The Age of the Sculptor Dwarf Spheroidal Galaxy from Imaging with WFPC2
Ballester, Gilda E.; Grillmair, Carl; Krist, John E. +17 more
From images taken with the Hubble Space Telescope's WFPC2, we have obtained photometry of a field in the Sculptor dwarf spheroidal galaxy to 3 mag below the main-sequence turnoff. We determine an age equal to that of the earliest globular clusters for the bulk of the stars in our field of view. We attempt to constrain the star formation history of…
Internal Kinematics of Blue Canada-France Redshift Survey Galaxies at Z ~ 0.6
Crampton, David; Schade, David; Mallén-Ornelas, Gabriela +1 more
We present the results of a study of the internal kinematics of luminous star-forming galaxies in the 0<z<0.8 range, with the aim of investigating the nature of the blue galaxies that cause the largest changes in the luminosity function at z>=0.5. New kinematic data are analyzed for a sample of 24 galaxies from the Canada-France Redshift …
Electron heat flux constraints in the solar wind
Gary, S. Peter; Daughton, William; Skoug, Ruth M.
Enhanced fluctuations from electromagnetic heat flux instabilities may, through wave-particle scattering, constrain the electron heat flux which flows parallel to the background magnetic field in the solar wind. A corollary of this hypothesis is that instability thresholds should correspond to observable bounds on the heat flux. Here plasma and ma…